Liquid level gauge



Sept. 21, 1943. v D. R. YARNALL 2,330,102

LIQUID LEVEL GAUGE Original Filed May 16, 1940 a W if} Patented Sept.21, 1943 LIQUID LEVEL GAUGE David Robert Yarnall, Philadelphia, 2a.,assignor to Yarnall-Waring Company, Pa., a corporation oi Pennsylvania.

Philadelphia,

Original application May 16, 1940, Serial No.- 335,597. Divided and thisapplication May 15, 1941, Serial No. 393,530

8 Claims. (Cl. 73-330) My present invention, intended for any use towhich it may be adapted, relates tocfiat glass water-level gauges. 7

A purpose of the invention is to cushion the pressure upon a flat insertand at the same time to take care of expansion and contraction andparticularly to compensate for variation in expansion and contraction ofparts with temperature change and for deflections due to variations instress with change in internal pressure.

A further purpose is to secure" uniform compression of the fiat glassinsert upon its seat by resilient individual springs held down by bolts,limiting and predetermining the pressure of each bolt upon the coverplates.

A further purpose is to make it impossible for an operator whenreplacing a flat glass plate to crush the glass by too much pressure atone or more of the studs bolting down the cover.

A further purpose is to prevent a pressure seal gasket under a fiatgauge glass from blowing back into the visible gauge space when anoperator blows down the gauge by a retaining strip welded to the gaugebody.

Further purposes will appear in the specificationand in the claims,

I have elected to show my invention in a few only of its forms,selecting forms, however, that are practical and efiicient in operationand which well illustrate the principles involved.

The present application is a division of my application for Resilientprotection for fiat gauge glasses, Ser. No. 335,597 filed May 16, 1940,

Figure 1 is an elevation intended, except for the features indicated atl6 and 26, for a conventional showing of any structure adapted to embodymy present invention.

Figure 2 is a section of Figure 1 taken upon the line 2-2 thereof.

Figures 3 and 4 are fragmentary sections corresponding generally toFigure 2 but showing modifications.

Figure 5 is an assembly view of the holding means for a cover.

Figure 6 is an elevation of a stud and its associated parts, intendeditself to embody a new article of commerce.

Figure '7 is a perspective of a. conical spring.

Like numerals refer to like parts in all figures.

Describing in illustration and not in limitation and referring to thedrawing:

The gauge structure illustrated comprises a body I to which fiat glassplates II are held by covers l2.

In the form of Figures 1, 2, 3, and 6, studs I3 carry spring cones ll bywhich the parts are held in place, resiliently pressing gaskets l5.

In all of the forms retaining strips l6 restrain inward movement of thepacking. Upper and lower conventional outlet nipples I1 and 18 are shownfor connection to the steam and water spaces, respectively, of a boiler.

The body l0 and covers l2 are longitudinally through-slotted at l9 forintermediate portions of their lengths forming long straight slots withcurved ends. The body is bored and counterbored at its ends at 20 and 2|to receive the nipples l1 and I8. Covers l2 and body I0 are oppositelyrecessed at 22 and 23 about the through slot H) .to receive the fiatglasses II, and are formed at the bottoms of the recesses 22 and 23 toseat the endless gaskets IS. The bottoms of recesses 22, 23 in body I 0are tapered so as to be shallower at the outsides than at the insides toprovide outward flares at 24 so that the progressive outwardconstriction of the gasket space causes the high pressure within thegauge compartment to tighten the gasket in the space as it presses thegasket outwardly, Each gasket adjacent a strip 5 seals againstitstapered seat and against the inner face of the glass.

One feature of the invention is directed to the retaining strips 16. Acontinuous or endless retaining strip integral with the body andimmediately inwardly adjacent a gasket of the type indicated has beendisclosed in an application of Walter J. Kinderman, Patent No.2,201,542, issued May 21, 1940 for Gauge glass with gasket and gasketseat.

Applicant finds this integral construction awkward and diflicult tomanufacture. The Kinderman groove is easily out along the straightlengths by a milling cutter but this cutter if of' full groove sizecannot be turned to follow the end half circle paths without destroyingthe inner groove walls; and if of less than full groove size it is stilldifficult to finish the groove properly at these curved ends.

Applicant uses strips which are separate and which are welded againstthe inner edge of the indicator body or other body seen in Figure 1. Thestrips are not needed as much at the ends but may follow the curves atthe ends. A space 26 is indicated between the opposing ends of thestrips Hi. This space may be large or small. It is intended toaccommodate temperature changes during welding.

A principal feature of the invention is directed to the resilient,limited, and predetermined compression of the covers [2, upon theglasses ll, se-

curing right compression upon the glasses ll despite small dimentionalvariations of any of the gauge members and despite any other smalloutward variation of either glass.

A variety of types of stud assemblies is shown each described in detailbecause it forms or may form a part of the assembly by which thecushioning of the plates is effected, and a limit is placed upon theextent to which compression may be carried, avoiding accidental carelessor reckless seating of the individual studs of whichever form shown andpermitting the assemblage to be made safely and yet at much higher speedthan where individual judgment is required. Each stud 13 comprises athreaded end 28, a shoulder 29 adjacent the thread, an enlarged section30 which provides the shoulder, a head 3| by which the stud is screwedin place and a. reduced crosssection or neck 32 between the enlargedsection 30 and the inward face 33 of the head.

It will be noted that what has been treated as a stud above is in effecta bolt when the work is finished. The bolt has a threaded end to fitinto the body, and the head is fixed with respect to the said threadedend. This is true whatever the previous condition or history of thefastening may be, and notwithstanding that in forms where I contemplatestarting with a double threaded stud and placing a nut upon the exposedpart of the stud, the rigidity of the head is given not by integralitybut by fastening a nut to its thread.

About a reduced neck of the bolt is located spring material. In Figures2, 3 and 6 appear a plurality of spring cones I4, placed base 34 to base34 or crown 35 to crown 35 so that they are cumulative in their springeffects. Two are used in Figure- 2, and three in Figures 3 and 6. Inanother form (Figure 4) a spring i4 is used.

The shoulder need not be extensive. It need be enough definitely to seta limit to the seating of the studs, as distinguished from allowing theextent of insertion of the studs to depend upon the uncertainties of thecutting of the thread. Excellent results have been secured with but afew hundredths of an inch of shoulder.

The inner diameter 36 of the inner cone considered as a retainingwasher, or of the spring, is such that it fits loosely upon the neckportion of the stud but is too small to slip off from the stud.

Where the head is originally separate and has been added (Figures 2 and4) this inner diameter 36 may be quite noticeably smaller than eitherthe enlargement or the head and the cones may be applied before the headis applied. This offers opportunity for individual adjustment of thepressure because the head can be located at different distances from theshoulder and hence can provide for different pressures upon the springwashers or spring.

The studs l3, together compressing the cover upon the glass ll, threadhome into the body ill until shoulders 29 engage the outer face of thebody about the thread. Meantime spring cones M, or springs I4 arecompressed between inwardly directed (head) face 33 carried by the studand the surface of th cover about the stud.

It will be seen that each stud assembly comprises a stud i3 providing aninwardly directed shoulder that determines the operating position of thestud when threaded into the body, and a head setting a predetermineddistance allowed for cover thickness and compression spring cones ofspring. Moreover the group of spring cones I4 or spring is kept inassembly with the stud.

The present invention compensates for the weaving of plate gauge glassescaused by the body of the gauge heating up first and the heating of thecover lagging sufficiently to cause a slip between the body and thecover.

It is intended also to provide tolerances ample for avoidance of injuryby reason of accidental variation of dimensions from the limits set.

The position of the stud head with respect to the shoulder engaging thebody forms the limit to avoid excessive compression. The extent ofcompression of the spring cones or springs used must be such as, withthe variations met with in practice in expansion etc., avoids excessivecompression with maximum stress on the one hand and insures that withminimal stress there shall not be low enough pressure to permit leakage.

After standardization of equipment, determining extents of compressionof packing at the pressure contemplated, extents of compression ofsprings for these pressures, number of cones or length of springsdesirably used, and, as derived from them, over-ail spacing between theshoul-. ders of the stud and the under sides of th heads, the studs canbe duplicated as standard for the equipment thus tested. However, thetests for a new piece of equipment'are simple in determination of thespacing to be given between the shoulders and the under sides of thehead either for all the studs of this new equipment or for individualstuds, if for any reason it be desired to give them differentcharacteristics.

In practically determining the stud d mensions the best means known byme is based upon use of a stud of which an example is shown in Figures 2and 4 having a thread at each end, an intermediate enlargement forming ashoulder and a neck above the intermediate enlargement. This stud isscrewed home so as to shoulder against the body, and the packing andcover are put in place over the stud. The cones or spring desired are oris mounted over the outer thread and a nut is screwed down upon itsouter thread until, as determined by the wrench leverage and thepressure applied, the desired spring pressure has been reached. Theposition of the nut upon the screw is then marked for duplication afterremoval of the nut and stud, or the nut and stud are drilled and pinnedtogether as in Figure 4 to set the nut. The stud is removed and the nutis welded to the stud at the desired position or the position to whichthe nut is set by the pin is maintained.

In either event above this individual stud will then serve the purposeat the position at which it has been set or if the studs are to beuniform may be used as a model for the production of other studs. Thenumber of spring cones used or the length of spring applied depends uponthe intended tolerance. For example, if the range of compressivedistance by which compression of a single cone may be acceptable be asixty-fourth of an inch a single cone would give but a sixtyfourth inchof permissible variation, whereas the two cones of Figure 2 or the threecones of Figures 3 and 6 would give a thirty-second of an inch or threesixty-fourths inch permissible variation, respectively. For the samereasons ad-- ditional coil length of any given spring increases thetolerance in the use of that spring,

In the unusual case where the studs are to be differently set for thesame cover the procedure above can be followed and the individual studsas determined can be marked for their selected positions.

Where, as in Figures and 6, the "head is integral with the stud, thehead is left "long? initially. The cones or spring are or is passed overthe enlargement 30 and are tightened against the cover. If it be seenthat the cones or spring are or is unduly compressed in screwing thestud home, the under face of the head is cut away until the distance isright and this stud is used for a sample. In the solid head structurethe cones are made a tight enough fit over the stud shoulder so that,though they can be forced over to occupy the neck position they cannotbe removed without application of considerable force and will not falloff. The spring, correspondingly tight over the shoulder, can bepartially unwound for passage over the shoulder and merely resumes itscoil tightness within the stud neck.

This condition in which the spring washer can be forced over theshoulder or body to fit into the recess is viewed herein as a forced fitand means that the inside diameter of the spring is approximately equalto the outside of the body of the bolt, and the spring can be forcedover it. This is what is ordinarily known in machine shop practice as aforced fit or drive fit."

The data required for design of studs for new conditions may also bedetermined from a laboratory study of the characteristics of theelements involved. For example, the amount of compression of standardcones and springs for each of different pressures in pounds may bedetermined by experiment, as also the extent of compression of differentpackings at various pressures. Such information is also available frommanufacturers of the materials. From this data and the thickness of theseveral comparatively incompressible parts the distance between the studshoulder and the under face of the nut or head upon the stud is easilyworked out.

The preferred form of spring material is the spring cone.

It will be evident that when the reduced portion next to the head iscalled a neck this does not indicate that there need be much differencein diameter between it and the enlargement bounding it toward theshoulder end of the stud or between it and the shoulder. It means merelythat the enlargement or the shoulder, if it serve the purpose, shall besufficient to prevent accidental removal of the cones or spring from theneck and that the neck shall be small enough for the cones or spring tomove upon it without undue friction. As there is no advantage in makingthe neck a close fit within the cones or spring there is a considerablerange of neck diameter which will be satisfactory.

It will be clear that the head performs two main functions affordingconvenient wrench engagement for setting the stud so that the shoulderof the stud abuts against the outer surface of the body, and pressingagainst the outer end of the spring or a cone to accomplish thecompression of the spring or cones. Where the smaller cone end of aspring cone extends outwardly the engagement with the cone to compressit will be satisfied by a very small engaging surface; and the functionof providing wrench engagement can be satisfied by a variety ofterminals well recognized in the stud art.

It will be evident that both of the means illustrated, though indifferent ways, provide resilient pressure, protecting by interventionof resilient means for taking up and equalizing the pressure in thetrain of pressure between the threaded retaining devices (whetherinitially in the form of studs without rigidly attached heads andsubsequently made into bolts or always with permanently attached headsconforming to the more usual type of bolts) and the glass and unifyingthe pressure as well as controlling the maximum pressure to be appliedby limiting the extent of movement of the devices. In the illustrationsequalization is by individual resilient studs (bolts) acting through acover, which cover is not limited in movement except by its pressureengagements through a gasket with the glass.

It will also be clear that the gasket is relieved from excessivepressure by either type of fastening devices, whether initially stud andnut or bolt. Both are capable of bringing pressure upon the cover, withintervening spring elements, and using shoulder limitation of thedistance to which they may be tightened.

The guard or protector 16 shown in Figures 1 and 2 is inserted withinthe upperpart of the through slot in the body and is held in position byany suitable means while its strips are welded to place, supplying aprotection against inward slip of the packing during blowing down of thegauge. This construction is more cheaply constructed than is theintegral form. Because of being separate metal it may be thinner than acorresponding integral construction would be.

Where I refer to parts in series, such as the series of spring washersseen in Figures 5 and ,6, I mean that the parts act in a train, onethrough another. In the present case no one of these spring washers inFigures 5 and 6 can be axially compressed without bringing compressivepressure upon the adjacent spring washer or washers in the seriesarrangement.

In View of my invention and disclosure variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the structure shown, and I, therefore, claimall such in so far as they fall within the reasonable spirit and scopeof my invention.

Havingv thus described my invention what I claim as new and desire tosecure by Letters Patent is: v 1

1. In a flat glass sight indicator for fluid levels, a bodythrough-slotted and recessed about the slot, a glass, packing betweenthe body and the glass, a slotted cover adapted to press the glass intofluid tight engagement with the packing, a plurality of bolts tightenedto hold the cover in position, spring means surrounding the boltsbetween the bolt heads and the glass for cushioning the pressure uponthe glass and means for stopping tightening of the bolts while thespring means is still resilient and before the spring of the means hasbeen fully taken up, whereby the pressure upon the glass is limited andis maintained as a resilient pressure as distin uished from from anunyielding pressure.

2. In a flat glass sight indicator for fluid levels, a bodythrough-slotted and recessed about the slot, a glass within the recess,packing between the body and the glass, a slotted cover, a plurality ofbolts holding the cover in position,

positively predetermined by the positions of the shoulders.

3. In a fiat glass sight indicator for water levels, a bodylongitudinally through-slotted and recessed about the slot, packingwithin the recess, a flat glass entering the recess and engaging thepacking, a cover through-slotted in agreement with the slot of the body,through which cover pressure is transmitted to the glass, a plurality ofthreaded retaining devices passing through the cover and entering thebody, holding it in position, the devices having heads and integralshoulders, and spring compression means located in series, one eachbetween each of the heads of the devices and the cover and whose extentof compression and consequent extent of pressure upon the cover islimited by engagement of the shoulders with the body.

.4. In a flat glass sight indicator for water level, a bodylongitudinally through-slotted and recessed about the slot, packingwithin the recess, a flat glass entering the recess and engaging thepacking, a slotted cover adapted to bring pressure upon the glass, aplurality of bolts passing through the cover and the threads enteringthe body to hold the cover in position, the extent of movement of thecover being determined by its engagement with the glass and the extentof pressure upon the cover being determined by the extent to which thebolts can enter the body and compression spring means surrounding thebolts and pressing against the cover, the extent of spring pressurebeing positively limited to leave the spring means but partlycompressed.

5. In a water level indicator, a body throughslotted for a portion ofits length and having a channel, a closure glass entering the channel,packing for the closure glass, a cover holding the closure glass inposition and having holes through the cover, studs passing through theholes in the cover, threaded into the body and having enlargementslimiting the extent of entry into the body, spring cones about the studsand heads permanently secured to the studs and by their positionslongitudinally of the studs determining the extent of compression of thespring cones when the studs have been screwed in until stopped by theenlargements.

6. In a flat glass sight indicator for water levels, a bodylongitudinally through-slotted and recessed about the slot, packingwithin the recess, a fiat glass entering the recess and en- 5 gaging thepacking, a slotted cover through which pressure is transmitted to thepacking, a plurality of studs threaded at both ends, one end of eachstud passing through the cover and entering the body, a shoulderadjacent the threaded end which passes through the cover, limiting theextents to which the individual studs can be screwed into the body,springs, one surrounding each stud outside the cover, nuts, one eachupon the second thread of each stud and pins, one passing through eachnut and stud to make each stud effective as a bolt and each nuteffective as a bolt head.

7. In a flat glass sight indicator for fluid levels,

a body, through-slotted and recessed about the slot, a glass, packingbetween the body and the glass, a slotted cover adapted to press theglass into fiuid tight engagement with the packing,

the cover having holes for iastenings, a plurality of studs extendingthrough the holes in the cover and threaded into the body as far as theycan be screwed, the studs being threaded at their ends farther from thebody, compression spring means surrounding the threads at the outer endsof the studs beyond the cover, nuts on the stud threads beyond thespring means and holding the spring means but partially compressed andpins passing through the nuts and threaded portions of the studs,whereby the nuts are fixed rigidly upon the stud ends, making the studseffective as bolts,

the pressure is maintained as resilient pressure and a maximum pressureupon the cover is set.

8. In a water level indicator, a body throughslotted for a portion ofits length and having a channel about the slot, a glass closure plate inthe channel, packing for the closure glass, a flange restraining thepacking against movement inwardly and welded to the edge of the throughslot, a slotted cover for the body holding the glass in place and meansfor pressing the cover 5 toward the body.

DAVID ROBERT YARNALL.

